People, resources and biodiversity: reading a model

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Table, World population (UN), with columns Milestone, UN figure

   8 billion reached, November 15, 2022; Time from 7 to 8 billion, about 12 years; Time from 8 to 9 billion (projected), about 15 years, to about 2037; Peak (projected), about 10.3 billion, mid-2080s; 2100 (projected), about 10.2 billion.

2. 1.

   Ari compares the UN's 12 years from 7 to 8 billion with the projected 15 years from 8 to 9 billion. What does it show?

   • Yearly growth speeds up, because 9 billion is more than 8 billion
   • Yearly growth stays the same, at about 1 billion per 12 years
   • The total will start to fall, because 15 years is longer than 12 years
   • Total still rises, but people added yearly fall from 83 to 67 million
3. 2.

   Bo reads the UN table for a report. Which claim does it support best?

   • Population keeps rising after the 2080s, with no peak in sight
   • Population reached 10.3 billion in 2022 and has fallen since
   • The UN counted 10.3 billion people alive in the mid-2080s
   • The UN projects a peak near 10.3 billion, then a slight fall
4. 3.

   Esme lists two UN numbers: 8 billion in 2022 and 9 billion around 2037. Which statement about them is true?

   • 8 billion is a projection from a model, and 9 billion is a count
   • Both are counts, because the UN reports a number each year
   • 8 billion in 2022 is counted; 9 billion near 2037 is projected
   • Both are projections made by the UN in 2024, using a model

5. Table, Forests (FAO, 2020 assessment), with columns Measure, FAO figure

   Forest area, 2020, 4.06 billion hectares (31% of land); Deforestation, 1990–2000, 16 million ha a year; Deforestation, 2015–2020, 10 million ha a year; Net forest loss, 1990–2000, 7.8 million ha a year; Net forest loss, 2000–2010, 5.2 million ha a year; Net forest loss, 2010–2020, 4.7 million ha a year; Net forest loss since 1990, 178 million ha.

6. 4.

   FAO says net forest loss fell from 7.8 to 4.7 million ha a year. What does Jun conclude about total forest area?

   • Forest area still shrank each decade, only more slowly
   • Forest area grew, because net loss went down
   • Forest area shrank faster in each later decade
   • Forest area has held the same since the year 2000
7. 5.

   In 1990–2000, FAO has deforestation at 16 million ha a year and net loss at 7.8. How much forest was gained each year, by Kira's subtraction?

   • About 7.8 million ha a year, the net loss itself
   • About 23.8 million ha a year, found by adding them
   • About 8.2 million ha a year gained back
   • About 0.5 million ha a year, found by dividing
8. 6.

   FAO says 4.06 billion ha of forest is 31% of land. What total land area does Luz get?

   • About 1.26 billion ha, found as 4.06 × 0.31
   • About 5.9 billion ha, found as 4.06 ÷ 0.69
   • About 5.3 billion ha, found as 4.06 plus 31%
   • About 13.1 billion ha, found as 4.06 ÷ 0.31

9. Use the table

   U.S. fish stocks, end of 2024 (NOAA Fisheries)

   Measure	Number of stocks
   Stocks managed	522
   With a known overfishing status	372
   On the overfishing list	23
   On the overfished list	42
   Rebuilt since 2000	51

10. 7.

    NOAA: 372 stocks have a known overfishing status, and 23 of them are subject to overfishing. What share is that for Noah?

    • About 6%, found as 23 ÷ 372
    • About 4%, found as 23 ÷ 522
    • About 62%, found as 23 ÷ 37.2
    • About 16%, found as 372 ÷ 23

11. Fishery computer model output (model data)

    Steady catch (thousand tons a year)	Stock the model settles at (thousand tons)
    40	about 890
    80	about 720
    100	about 500
    120	falls toward 0

    Note: The model starts at 1,000 thousand tons, the most the habitat holds. Each year the stock adds 0.4 × stock × (1 − stock ÷ 1,000) thousand tons.

12. 8.

    Ren raises the model's steady catch from 40 to 100 thousand tons a year. How much less fish settles in the water?

    • About 60 thousand tons less, found as 100 minus 40
    • About 500 thousand tons less, the stock left at 100
    • About 170 thousand tons less, from 890 down to 720
    • About 390 thousand tons less, from 890 down to 500
13. 9.

    In the model, Tala sets the catch at 120 thousand tons a year, above the table's largest steady catch. What happens to the stock?

    • It rises, because a bigger catch needs a bigger stock
    • It falls toward zero, since the stock cannot replace 120 a year
    • It settles at about 500, just like a catch of 100 would
    • It settles near 1,000, the most the habitat holds
14. 10.

    The fishery table is computer-model output. How should Zee use it?

    • Not used; a model cannot be checked against anything
    • To compare catch levels inside the model, not as measured catches
    • To name the real stock that will collapse in the next year
    • As NOAA's measured catch records for the year 2024 and later